Olefins, particularly linear alpha (terminal) and internal aliphatic olefins are useful petrochemical building blocks of significant industrial importance because of their good chemical reactivity, relatively low cost and availability. Important industrial applications for liquid olefinic hydrocarbons of six or more carbons per molecule include (a) conversion of the C.sub.7 -C.sub.9 range, by Oxo technology, to primary alcohols for plasticizer production, (b) the conversion of C.sub.11 -C.sub.14 range to linear alkylbenzenes for use in biodegradable detergent applications, (c) hydroformylation of C.sub.11 -C.sub.18 olefins to primary alcohols for use as their ethoxylated, sulphated and sulphonated derivatives in the detergent field, together with (d) miscellaneous applications as chemical intermediates in textile finishes, synthetic waxes and petroleum additives.
Unfortunately, the olefins prepared by dehydrogenation of paraffinic materials, particularly linear n-paraffins, are normally generated in low concentrations and are available only in the presence of much larger quantities of the corresponding saturated paraffinic starting material. Furthermore, where the carbon content of the paraffinic contaminent in the stream or charge stock is close to the carbon range of the olefins, separation of the two fractions cannot readily be achieved by distillation means.
Recently, the applicants have developed a liquid-liquid extraction procedure for separating liquid, aliphatic olefins of carbon number greater than six, from liquid olefin-paraffin mixtures that cannot readily be separated by distillation. The separation technique utilizes silver and copper salts solubilized in a low molecular weight alkanol or alkanol-polyether solvent mixtures.